Topic: GL-5 VS. Syncro's

[FourbangerYJ]

About 3 years ago I changed my tranny fluid. I added Mobil 1 75-90 GL5. Shortly after I saw that it could damage the syncros due to the sulfur. I didn't feel like swapping it out since I just spent over $30 on the Mobil 1.  And thinking it was an iternet myth.

So after about 10K miles I thought I would swap it out and see what it looks like.
I picked up some Redline MTL. I bought 5 bottles. After I got home I checked the FAQ's and found out I only needed 4 bottles :roll:

I drained the old stuff out and it looked pretty clean as it drain into the catch pan. Then from the catch pan into my used oil container. When I poured it out you could see the fluid had a bunch of bronze shimmery stuff. At the bottom of the pan you could see a real thin layer of bronze.

Well It looks like it's not a myth :oops:  Although I have no idea what it will look like when the time comes to change out the Redline. The tranny shifted real smooth. Even going from 3rd to 2nd. I am sure the Redline will shift as well.

It took about 3.5 bottles. I was going to pump in the fluid. I looked at the shifter boot and thought I would try a funnel with a long tube. It worked like a champ. Way faster and nothing spilled until it was full.

Pretty easy job. Just need a 15/16 socket for the fill plug and the drain plug. You can check the FAQ to see what other fluids will also work.

[Jeffy]

Must not be the reformulated GL-5.  It's in the FAQ, too. :wink:

http://www.4bangerjp.com/forums/viewtopic.php?t=422

[Dont Know Squat]

ok youve got me a little concerned considering I just put that oil in my jeep last week but this is what i found on mobil 1

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1_Synthetic_Gear_Lubricant_LS_75W-90.asp


Product Description
Mobil 1 Synthetic Gear Lubricant LS is a supreme performance, synthetic, multi-purpose, SAE 75W-90 automotive gear lubricant designed to meet the highest level performance requirements of modern passenger vehicles in all types of operating conditions including limited slip applications, as well as, deliver outstanding power transfer performance. Compared to conventional hypoid gear lubricants, Mobil 1 Synthetic Gear Lubricants LS 75W-90 performs exceptionally over a wide range of temperatures. Mobil 1 Synthetic Gear Lubricant LS 75W-90 achieves this through a unique proprietary formulation, that deliver optimized viscosity-temperature properties together with the highest level of inherent formulation stability and protects against thermal and oxidative degradation, wear and corrosion, viscosity loss associated with premature shearing. It also can be used in extended service and for aiding in fuel economy performance.

Mobil 1 Synthetic Gear Lubricant LS 75W-90 meets the most severe API Service MT-1 and GL-5 EP gear oil service classification.

Features & Benefits
Mobil 1 Synthetic Gear Lubricant LS 75W-90 combines wax-free synthesized hydrocarbon base oils and a specially designed extreme-pressure, limited-slip, sulfur-phosphorous additive system to provide a significantly higher level of performance in rear axles and differentials versus conventional fluids. Greater film strength at higher operating temperatures, reduced fluid friction and low-temperature application down to -50ºC provides significant advantages versus conventional mineral oil formulations. It reduces wear and spalling under the high speed, high torque and high horsepower conditions in competitive racing and high performance automobiles. This unique, high technology final drive gear lubricant has demonstrated outstanding performance including; fuel economy, extended drain, long-term friction retention, low-temperature capability and improved differential/axle durability and cleanliness. Key features and benefits include:

[Jeffy]

ok youve got me a little concerned considering I just put that oil in my jeep last week but this is what i found on mobil 1

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1_Synthetic_Gear_Lubricant_LS_75W-90.asp


Product Description
Mobil 1 Synthetic Gear Lubricant LS is a supreme performance, synthetic, multi-purpose, SAE 75W-90 automotive gear lubricant designed to meet the highest level performance requirements of modern passenger vehicles in all types of operating conditions including limited slip applications, as well as, deliver outstanding power transfer performance. Compared to conventional hypoid gear lubricants, Mobil 1 Synthetic Gear Lubricants LS 75W-90 performs exceptionally over a wide range of temperatures. Mobil 1 Synthetic Gear Lubricant LS 75W-90 achieves this through a unique proprietary formulation, that deliver optimized viscosity-temperature properties together with the highest level of inherent formulation stability and protects against thermal and oxidative degradation, wear and corrosion, viscosity loss associated with premature shearing. It also can be used in extended service and for aiding in fuel economy performance.

Mobil 1 Synthetic Gear Lubricant LS 75W-90 meets the most severe API Service MT-1 and GL-5 EP gear oil service classification.

Features & Benefits
Mobil 1 Synthetic Gear Lubricant LS 75W-90 combines wax-free synthesized hydrocarbon base oils and a specially designed extreme-pressure, limited-slip, sulfur-phosphorous additive system to provide a significantly higher level of performance in rear axles and differentials versus conventional fluids. Greater film strength at higher operating temperatures, reduced fluid friction and low-temperature application down to -50ºC provides significant advantages versus conventional mineral oil formulations. It reduces wear and spalling under the high speed, high torque and high horsepower conditions in competitive racing and high performance automobiles. This unique, high technology final drive gear lubricant has demonstrated outstanding performance including; fuel economy, extended drain, long-term friction retention, low-temperature capability and improved differential/axle durability and cleanliness. Key features and benefits include:

Which is why I said it must not have been reformulated.  If it's MT-1 then it is reformulated GL-5 which is syncro friendly.  It's also in the FAQ under the link I provided.

[FourbangerYJ]

I have not seen any of the Mobil 1  MT1. Had no idea there was such a thing. The stuff I was used was the standard M1 gear oil.

I would imagine that even with the proper fluid you will still see some broze in the oil when changing it. The synco's are a wear item so there will always be some wear. Question is how much more wear do you get by using the wrong stuff??